From Patent Application EP 1 371 597 A1 a sheathed rope used as suspension means for elevators has become known. The rope has inner strand layers and outer strand layers, a strand layer consisting of several twisted strands and the direction of twist of the inner strand layer being opposite to the direction of twist of the outer strand layer. The tensile strength of the inner strand layer is higher than the tensile strength of the outer strand layer. Each strand is constructed of twisted and impregnated aramid synthetic fibers. The service life of the outer strand layer is less than the service life of the inner strand layer. For the purpose of monitoring the rope, individual strands of the outer strand layer are provided with electrically conducting wires, every two adjacent strands being provided with electrically conducting wires that mutually abrade and thereby promptly detect the expiration of the service life of the rope or the end of the rope life of the rope.
From Patent Application EP 0 731 209 A1 a sheathed rope used as suspension means for elevators has become known. The rope has inner strand layers and outer strand layers, a strand layer consisting of several twisted strands and the direction of twist of the inner strand layer being in the same direction as the direction of twist of the outer strand layer. Each strand is constructed of twisted and impregnated aramid synthetic fibers. For the purpose of monitoring the rope service life or state of wear of the synthetic fiber rope, in each case one strand of a layer of strands is provided with electrically conductive carbon fibers. In regular operation, it is always the case that the carbon fibers either as a result of excessive stretching or an excessive number of reverse bendings snap or break sooner than the load-bearing aramid fibers of the strand. With the aid of a voltage source, the number of snapped carbon fibers can be determined. So that the residual load-bearing capacity of the synthetic fiber rope can be assured, only a certain percentage of the carbon fibers may fail. The elevator is then automatically driven to a predetermined stop and switched off.